I have Samsung (1T) SSHD drives on all my 4 computers and it also deletes the cache in the 8 gigs of flash just about every 10 or 12 hours and instead if a 35 second start up time to reverts back to a 3 minute startup time until I restart the computer 10 more times and so on the next day
The flash/disk aspect of your SSHD is not visible to Windows, it will just see it as a drive. The drive itself manages what is stored in the flash portion and when it is moved to the disk portion based on usage patterns. This does mean that some things will vary in load time from boot-to-boot depending on if they are in flash or disk at that time. I guess Windows could be seeing this as a performance problem and so taking maintenance action.
My drive is a Samsung Pro NVMe device with over 60% space free. I have no idea why Windows thinks this requires a disk cleanup.
All that I can see is that my SSHD just a few seconds ago as I restarted lost the flash memory on the drive and also lost all thumbnails at the same tine I restarted the computer 8 more times and it is all back to a 35 second start.
Both of these problems must be tied together
My drive is only about 40 % full
Driving me crazy
Steve
Have a fun day